Power electronics devices employ electronics packages (devices) that generally contain electrical circuitry for conducting electrical current which, in turn, generates thermal energy (i.e., heat). Automotive high-power electronics typically generate a significant amount of thermal energy during operation. Excessive heat build-up may cause reduced performance including electrical circuit failure. Thus, thermal energy must be dissipated and transferred away from the electronics to ensure proper operation of the assembly. Additionally, the power capability of the electronics package(s) and size of the electronics assembly generally depend upon the amount of heat dissipation that may be achieved.
To enhance thermal energy dissipation, some electronics assemblies employ a heat sink in thermal communication with the electronics. This may include arranging the heat sink near one side of the electronics package(s) and/or on one side of the circuit board substrate. When employing a heat sink on one side of the circuit board, thermally energy dissipation from the electronics package to the heat sink is limited by the thermal conductivity of the circuit board substrate material. As a consequence, the overall heat dissipation achieved is limited.
To further enhance the heat dissipation through a circuit board substrate, it has been proposed to employ power semiconductor devices soldered to a top conductor of an electronics substrate that utilizes the substrate as the primary thermal path to a metal heat sink. The thermal conductivity of conventional substrates, such as thick film on alumina substrates, may not be acceptable for high-powered automotive applications. One proposed solution to enhance the thermal conductivity is to employ more expensive substrate materials, such as aluminium nitride, silicon nitride, and other expensive materials, which add to the cost of the circuit board and the overall electronics assembly.
An alternative proposal to changing substrate materials is to drill or punch vias (openings) into the substrate and fill the vias with a high thermal conductivity material to form a plurality of thermal conductive vias extending through the circuit board. The thermal conductive vias are formed of a material having a higher thermal conductivity than the circuit board substrate and provide a thermal communication path from the electronics package(s) to the underlying heat sink device. In the conventional assembly, the thermal conductive vias are generally parallel to each other and extend straight through the circuit board substrate from the top surface to the bottom surface.
While the prior cooling approach employing a plurality of thermal conductive vias has achieved enhanced heat dissipation from the electronics devices, the heat dissipation path is generally limited. It is therefore desirable to provide for enhanced thermal energy dissipation through a substrate. In particular, it is desirable to provide for a cost affordable electronics assembly having enhanced dissipation of thermal energy through a circuit board substrate.